1. Field of the Invention
The present invention relates to a disk drive, and more particularly, to a suspension assembly of an actuator for a disk drive supporting a slider on which a rear/write head is mounted.
2. Description of Related Art
Hard disk drives (HDDs), which are data storage devices used for computers, use read/write heads to reproduce or record data with respect to a disk. In the HDD, the head performs its functions while being moved by an actuator to a desired position in a state of being lifted to a specified height from a recording surface of a rotating disk.
FIG. 1 is a plan view illustrating the configuration of a conventional hard disk drive. Referring to FIG. 1, the hard disk drive includes a spindle motor 12 installed on a base member 10, a disk 20 which is one or more disks and installed on the spindle motor 12, and an actuator 30 to move a read/write head (not shown) for reproducing and recording data to a specified position on the disk 20. The actuator 30 includes a swing arm 32 rotatably coupled to a pivot bearing 31 installed on the base member 10, a suspension assembly 40 installed at one end portion of the swing arm 32 and supporting a slider 44, on which the head is mounted, toward a surface of the disk 20 to be elastically biased, and a voice coil motor (VCM) to rotate the swing arm 32. The voice coil motor includes a VCM coil 36 coupled to the other end portion of the swing arm 32, a lower yoke 37 installed under the VCM coil 36, and a magnet 38 attached to an upper surface of the lower yoke 37. Although not shown in the drawing, the voice coil motor may further include an upper yoke installed above the VCM coil 36 and a magnet attached to a lower surface of the upper yoke.
The voice coil motor having the above configuration is controlled by a servo control system to rotate the swing arm 32 in a direction following the Fleming's left hand rule by the interaction between current applied to the VCM coil 36 and a magnetic field formed by the magnet 38. That is, when the power of the hard disk drive is turned on and the disk 20 starts to rotate in a direction D, the voice coil motor rotates the swing arm 32 counterclockwise, that is, in a direction A, to move the slider 44 on which the read/write head is mounted toward a position above the recording surface of the disk 20. The slider 44 is lifted to a specified height from the surface of the disk 20 by a lift force generated by the rotating disk 20. In this state, the head mounted on the slider 44 reproduces or records data with respect to the recording surface of the disk 20.
When the hard disk drive is not in operation, that is, the rotation of the disk 20 is stopped, the head is parked at a position out of the recording surface of the disk 20 so that the head does not collide against the recording surface of the disk 20. The head parking system can be classified into a contact start stop (CSS) method and a ramp loading method. In the CSS method, a parking zone where data is not recorded is provided at an inner circumferential side of the disk 20 and the head is parked in the parking zone in a contact manner. However, in a head parking system adopting the CSS method, since the parking zone needs to be provided at the inner circumferential side of the disk 20, a data storage is lessened. Thus, to meet the recent trend toward a higher data recording density, a head parking system adopting the ramp loading method which can secure a larger data storage space is wildly adopted.
In the ramp loading method, a ramp 50 is installed outside the disk 20 and the head is parked on the ramp 50. To this end, the suspension assembly 40 has an end-tab 45 supported by the ramp 50. When the power of the hard disk drive is turned off and the disk 20 stops rotating, the voice coil motor rotates the swing arm 32 clockwise, that is, in a direction B, and accordingly, the end-tab 45 is moved from the disk 20 to the ramp 50 to be supported by the ramp 50.
In a state in which the read/write head is parked on the ramp 50, when an external impact or vibrations are applied to the disk drive, the actuator 30 is rotated and moved toward the recording surface of the disk 20 from the ramp 50. In this case, the recording surface of the disk 20 may be damaged by the head which contacts the same. Thus, in a state in which the disk 20 stops rotating and the head is parked on the ramp 50, the actuator 30 needs to be locked at a specified position so as not to rotate. For this purpose, an actuator latch 60 is provided.
FIGS. 2 and 3 are a perspective view and a side view, respectively, illustrating the suspension assembly of an actuator shown in FIG. 1.
Referring to FIGS. 2 and 3, the suspension assembly 40 includes a load beam 41 coupled to an end portion of the swing arm 32, the end-tab 45 extending from an end portion of the load beam 41, and a flexure 43 supporting the slider 44 on which the head is mounted. The load beam 41 and the flexure 43 are typically formed of a thin stainless steel plate. The load beam 41 has a thickness of about 0.5 mm to have a certain rigidity while the flexure 43 has a thickness of about 0.2 mm, which is relatively thinner than the load beam 41, so that a free movement is possible as described later. A rear end portion of the flexure 43 is fixed by welding to a surface of the load beam 41, that is, a surface facing the disk 20 while a leading end portion thereof is freely moved up and down. A dimple 42 protruding toward the flexure 43 is formed on the load beam 41. The dimple 42 provides a specified elastic force to the flexure 43 so that the flexure 43 can freely move. Accordingly, smooth pitching and rolling of the slider 44 attached to the flexure 43 are possible.
A protrusion 46 protruding toward a support surface 51 is generally formed on the end-tab 45 to reduce a contact area between the end-tab 45 and the support surface 51 of the ramp 50.
However, in the conventional suspension assembly 40 having the above configuration, when an external impact is applied, the leading end portion of the flexure 43, that is, a free end, vibrates up and down. If the external impact is large enough to cause severe vibrations, the flexure 43 may be bent and deformed or the sliders 44 facing each other bump against each other so that the heads mounted on the sliders 44 may be damaged.